Public bug reported:
Changeset I3447ea5bcb7c57365c6f50efe12a1671e86588b3 added a
binding_index column to the RouterL3AgentBinding table, which is unique
with the router_id. However, the current logic isn't concurrent safe as
some concurrent cases can raise a DBDuplicateEntry (if the same
binding_index is being used by 2 different workers).